Many-to-Many Relationship in SQL

Many-to-Many Relationship in SQL — a practical guide to SQL many-to-many relationship with clear examples you can reuse in real projects.

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Short description

Add payload columns (e.g., enrolled_at) on the junction when needed.

M:N sketch

CREATE TABLE course_user (
  course_id INT UNSIGNED NOT NULL,
  user_id INT UNSIGNED NOT NULL,
  enrolled_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (course_id, user_id)
);